One type of rotary fluid machine comprises a rotor and a stator which together defined a working chamber. A number of lobes are formed on one of the rotor and the stator, with a plurality of gates being supported by the other. Inlet and outlet ports are provided on opposite sides of each lobe to allow fluid to flow into and out of the working chamber. When the machine acts a motor, high pressure fluid is fed into the machine and enters the working chamber through the inlet ports. The working chamber is divided into sub-chambers between adjacent gates. The fluid exerts pressure on the gates causing the rotor to rotate. As this rotation occurs, eventually the fluid in a sub chamber is brought into fluid communication with an outlet port and vented through the machine. While this is occurring, high pressure fluid continues to enter the working chamber through the inlet ports and exerts pressure on other gates to maintain relative rotation between the rotor and stator.
When used as a pump, another machine provides torque to the rotor to cause relative rotation between the rotor and stator. As this occurs, the gates displace fluid in the pump forcing the fluid to flow through outlet ports and create a relative lower pressure state drawing further fluid through inlet ports into the working chamber.
Numerous factors govern the efficiency and reliability of fluid rotary machines. Machine performance and reliability is also substantially affected by the nature of the fluid passing through the machine. For example, fluids passing through the machine which contain abrasive products and/or corrosive substances are often problematic.